Roller Ball Research Articles

Multi-Response Optimization of Single Point Incremental Forming of Al 6061 Sheet Through Grey-Based Response Surface Methodology

The single point incremental forming process (SPIF) is materialized to form the desired shapes in low-cost sheet metal processing and well suited for low batch components and customized designs. Many modifications have been attempted in recent years to maximize the formability, geometric accuracy and quality of the SPIF formed parts. In this work, an attempt has been made to analyse the influence of process parameters namely ball tool diameter, step size, spindle speed and sheet thickness on final wall thickness, forming force and surface roughness. The optimized results exhibit the desirable formability when the roller ball tool diameter of the tool is 12 mm. The results also project that formability of the sheet metal is minimized when the spindle speed is increased and the ball diameter maximizes the accuracy and surface roughness. Also minimizing the step size increases the product quality features. Upon conducting this multi-response optimization by grey based response surface methodology (RSM) technique It is identified that 12 mm ball diameter of the tool, 0.25 mm step size, 2445 rpm spindle speed, and 2 mm sheet thickness are the obtained optimized SPIF process parameters as confirmed through confirmation experiments.

The Impact of SARS-CoV-2 on Patients With Lower Urinary Tract Symptoms (LUTS).

During the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, the management of patients with lower urinary tract symptoms (LUTS) underwent dynamic adjustments in response to an evolving understanding of the virus's impact on different patient populations. Healthcare practitioners reevaluated therapeutic approaches for conditions like benign prostatic hyperplasia (BPH), considering the potential implications of this condition on the severity and progression of coronavirus disease 2019 (COVID-19). This study aims to investigate potential correlations between SARS-CoV-2 infection severity, exacerbation of LUTS, and BPH progression. This retrospective study includes patients hospitalized in our Urology Department between January 2021 and January 2023, presenting with both SARS-CoV-2 and BPH. Their ages ranged from 57 to 88 years, with a mean age of 65.4 years. The diagnosis of BPH relied on a diagnostic triad consisting of digital rectal examination, biological markers (including prostate-specific antigen (PSA) and free PSA, and ultrasound examination, with both conditions confirmed based on test results. Transurethral resection of the prostate (TURP) procedures utilized monopolar Karl Storz resection equipment, using sorbitol and bipolar Olympus devices for transurethral resection of the prostate in saline (TURPis). Haemostasia was performed using roller balls. Anticoagulation followed a prescribed scheme by cardiologists and infectious disease specialists. Statistical analysis was conducted using IBM Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp. Among the 138 hospitalized patients affected by both BPH and COVID-19, 18 required emergency endoscopic procedures (specifically TURP or TURPis) to achieve hemostasis (Figures 1, 2). These individuals presented persistent hematuria despite conservative treatments. The mean duration of surgery was 57.9 minutes. Patients who underwent surgery had a longer average hospital stay compared to those who did not, with durations of 10.5 days versus 7.5 days, respectively. Additionally, urethrovesical catheter insertion was necessary in 29 cases due to acute urinary retention or worsening voiding symptoms during hospitalization. These patients are scheduled for further urological evaluation following the resolution of the COVID-19 episode. In a cohort of 53 patients for whom data were accessible, comparisons were made between the pre-COVID status and the levels of the International Prostate Symptom Score (IPSS), post-voiding residue (PVR), and quality of life (QoL). The findings revealed a mean pre-COVID IPSS value of 11.6 and a COVID-related value of 14.2, with a statistically significant difference noted (p < 0.05). The mean pre-COVID PVR was 42.3 cm2, whereas during the COVID-19 period, it measured 62.5 cm2, also exhibiting a significant difference (p < 0.05). Additionally, the QoL showed a mean pre-COVID-19 score of 2.4 and a COVID-19-associated score of 2.9, again demonstrating statistical significance (p < 0.05). The onset of the SARS-CoV-2 pandemic posed novel challenges in the medical realm, impacting the approach to BPH management. A common practice was delaying treatment for chronic BPH until viral infection remission to reduce associated risks. Additionally, our study revealed a worse evolution in LUTS among individuals with severe COVID-19 symptoms.

Substrate Versatile Roller Ball Pen Writing of Nanoporous MoS2 for Energy Storage Devices.

Low-cost fabrication of customizable supercapacitors and batteries to power up portable electronic devices is a much-needed step in advancing energy storage devices. The processing methods and techniques involved in developing small-sized entities in complex patterns are expensive, tedious, and time-consuming. Here, we demonstrate the fabrication of customizable electrochemical supercapacitors and batteries by simply employing the universal and conventional paradigm of direct pen writing with hands and evaluating their energy storage performance. The fabrication technique involves the refilling of MoS2 ink into the pen and then scripting of MoS2 nanostructures onto various substrates. The electrode material employed here consists of nanoporous microspheres of MoS2 synthesized by a simple one-step hydrothermal method. Direct pen writing with porous MoS2 in complex patterns enables easy, affordable, and simple fabrication of energy storage devices as and when required based on user choice toward distributed manufacturing and sustainability.

Study on Preparation of Homogenized Highly Dispersible AlON Powder

The quality of Aluminum oxynitride (AlON) powder is the main factor affecting the properties of ceramics. To accurately control the nitrogen AlON content and improve the dispersion degree of powder, AlON powder was prepared from γ-Al2O3 and activated carbon powder by carbothermic reduction and nitridation. The uniformity of distribution of raw materials and the dimension and microstructure of AlON powder was controlled by changing the time and rotation rate of the ball milling process. The influences of ball milling process parameters on the microstructure and distribution uniformity of Al2O3/C mixed powder, microstructure, and particle size of AlON powder were studied. The results show that powder agglomeration was effectively reduced, and the uniformity of raw material distribution was increased by controlling the time and rotation rate of the ball milling process. The Al2O3/C mixed powder has good particle size and uniform distribution with roller ball milling for 24 h. After holding the powder at 1700 °C for 60 min, the homogenized AlON powder was obtained, and the residual carbon content was about 0.04 wt%. When the time of planetary ball milling at 250 rpm was 16 h, highly dispersible AlON powder was obtained.

Study on Single Point Incremental Forming with the Roller Ball Tool for Increasing the Part Quality

Utilizing the common sheet metal forming method has many challenges in the field of sheet metal forming. Higher product quality with the lower quantities is an important requirement in this manufacturing field. The incremental forming process (IPF) is an innovation technology that can satisfy these requirements. In this paper, the single point incremental forming (SPIF) with different roller ball tool was researched. The results show that the smaller ball could provide a better product quality. However, the bigger ball could create a deeper geometry

Forensic Discrimination of Blue Ballpoint, Gel and Oil-Gel Pens: Application of Chemometrics to ATR-FTIR Data

The combination of advanced techniques with multivariate analysis methods are being used with great confidence by forensics experts due to their high precision and accuracy. The prime objective of present work was to explore the potential of chemometric tools in discriminating and predicting the blue pen inks when applied on Attenuated total reflectance Fourier transform infrared (ATR-FTIR) data of pen strokes of different brands and models commercially available in Pakistani markets. The pen strokes on fine A4 paper and recycled A4 paper were obtained from 86 samples including ballpoints, gel, oil- gel and roller ball pens. ATR-FTIR spectra were first characterized for different functional groups present in ink pigments however, they were apparently indistinguishable having some common functional groups. After spectra preprocessing the principal component analysis (PCA) and agglomerative hierarchical cluster analysis (AHC) showed that pen strokes could be distinguished. Both PCA and AHC analyses showed that ballpoints and gel pen could be discriminated and grouped separately. PCA analyses also showed the discrimination between local and foreign brands of ballpoints. Finally, classification method partial least squares-discriminant analysis (PLS-DA) was successfully applied for the classification and subsequently for the identification of type of pen used in personnel’s signature to mimic a forensic case. To evaluate PLS-DA classification performance, the classification parameters such as sensitivity, specificity, accuracy and precision were also derived from confusion matrix. Overall, this work emphasized the worth of multivariate analysis in classification and prediction of type of writing pen in a document as a forensic study.

Preparation and wear resistance of dual-scale structure cemented carbide spherical teeth

Based on commercially available WC (particle sizes of 0.9 μm and 2.4 μm) and Co, a dual-scale structure WC-6Co cemented carbide was prepared via conventional roller ball milling and following vacuum sintering. Effect of ball milling process on the microstructure, densities and mechanical properties were investigated together with the toughening mechanism of the dual-scale structure. The results showed that the dual-scale structured cemented carbide has excellent comprehensive mechanical properties, and its transverse rupture strength, hardness and fracture toughness are 3077 MPa, 1570 HV30 and 10.6 MPa m1/2, respectively. The drilling spherical teeth was prepared by the optimized technology and subjected to impact wear test, the failure mechanism of cemented carbide spherical teeth in drilling operations is studied. The CM-2 spherical teeth had a more reasonable distribution structure of coarse and fine of WC, and exhibited more excellent impact wear resistance in the impact wear test of granite.

Deep cold rolling of single crystal nickel-based superalloy CMSX-4

Nickel-based superalloys used in the aerospace industry are regularly subjected to high temperature and stress cycles. In order to extend component life, many components are subjected to a cold work process during manufacturing. One such technique is deep cold rolling, a highly controllable process which utilises a roller ball to impart cold work and deep compressive residual stress into a surface. In this study, local misorientation analysis of electron backscattered diffraction data has been used to quantify the surface cold worked layers in single crystal samples of the superalloy CMSX-4®, deep cold rolled with different pressures, ball diameters and roll orientations. As expected, it was found that greater pressure and ball diameter both increased the cold work depth, with pressure also affecting the amount of cold work per depth. Different roll orientations produced very similar distributions of cold work. In comparison with mechanical shot peening, another surface hardening technique, deep cold rolling is shown to produce a much deeper layer of relatively low cold work.

Trigger-Based Dexterous Operation with Multimodal Sensors for Soft Robotic Hand

This paper focuses on how to improve the operation ability of a soft robotic hand (SRH). A trigger-based dexterous operation (TDO) strategy with multimodal sensors is proposed to perform autonomous choice operations. The multimodal sensors include optical-based fiber curvature sensor (OFCS), gas pressure sensor (GPS), capacitive pressure contact sensor (CPCS), and resistance pressure contact sensor (RPCS). The OFCS embedded in the soft finger and the GPS series connected in the gas channel are used to detect the curvature of the finger. The CPCS attached on the fingertip and the RPCS attached on the palm are employed to detect the touch force. The framework of TDO is divided into sensor detection and action operation. Hardware layer, information acquisition layer, and decision layer form the sensor detection module; action selection layer, actuator drive layer, and hardware layer constitute the action operation module. An autonomous choice decision unit is used to connect the sensor detecting module and action operation module. The experiment results reveal that the TDO algorithm is effective and feasible, and the actions of grasping plastic framework, pinching roller ball pen and screwdriver, and handshake are executed exactly.

MP25-13 EXPERIENCE WITH COMPLETE TRIGONAL ELECTROFULGURATION FOR WOMEN WITH RECURRENT URINARY TRACT INFECTIONS: TWO YEARS FOLLOW-UP

You have accessJournal of UrologyInfections/Inflammation/Cystic Disease of the Genitourinary Tract: Kidney & Bladder I (MP25)1 Sep 2021MP25-13 EXPERIENCE WITH COMPLETE TRIGONAL ELECTROFULGURATION FOR WOMEN WITH RECURRENT URINARY TRACT INFECTIONS: TWO YEARS FOLLOW-UP Leopoldo Ribeiro-Filho, Felipe Hirasaki, Eduardo Miranda, Matheus Siqueira, Cristiano Gomes, Miguel Srougi, and William Nahas Leopoldo Ribeiro-FilhoLeopoldo Ribeiro-Filho More articles by this author , Felipe HirasakiFelipe Hirasaki More articles by this author , Eduardo MirandaEduardo Miranda More articles by this author , Matheus SiqueiraMatheus Siqueira More articles by this author , Cristiano GomesCristiano Gomes More articles by this author , Miguel SrougiMiguel Srougi More articles by this author , and William NahasWilliam Nahas More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002022.13AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Recurrent urinary tract infections (RUTI) have a negative impact on quality of life, contribute to antimicrobial resistance and have a significant economic burden. Long-term antibiotic therapy is the main treatment alternative but is often ineffective or poorly tolerated. In selected women, electrofulguration (EF) of trigonal lesions has been shown to reduce UTI episodes. In this study we evaluated the efficacy of complete trigonal EF for women with RUTI. METHODS: Between August 2006 and December 2017, 73 women with RUTI defined as three or more episodes of UTI per year were included in the study and completed at least two years of follow-up. All had undergone proper evaluation to exclude common causes of RUTI and all had squamous metaplasia and/or inflammatory lesions of the trigone or bladder neck. All had failed multiple antibiotic courses and were offered trigonal electrofulguration. Under anesthesia, endoscopic electrofulguration of the entire trigonal and bladder neck mucosa was performed using a roller ball. Biopsies were obtained prior to fulguration for histopathology analysis and in situ hybridization for Human Papiloma Virus (HPV). Patients were maintained on continuous bladder irrigation for a few hours and discharged home with no indwelling catheter. We evaluated the rate of UTIs during the initial two years of followup after fulguration based on symptoms and a positive urine culture. RESULTS: The median age was 64 years (range 17–76) and the median follow-up time after EF was 4.2 years (range 2.5 to 14 years). The procedure was well tolerated by all patients. Adverse events, most frequently disuria were mild and transient. In 24/76 (33%) patients bladder lesions in areas other than the trigone and bladder neck were also fulgurated. Histologically, squamous metaplasia (SM) was found in 31 (42%) patients and chronic erosive trigonitis (ET) in 42 (58%). HPV in situ hybridization was positive in 4/31 (13%) patients in the SM group and none in the ET group. Overall, 70/76 (96%) patients remained free of UTI episodes during the first year of follow-up, including 29/31 (94%) in the SM group and 41/42 (98%) in the ET group. At 2 years of follow-up, 15/31 (48%) in the SM group remained infection-free vs 27/42 (64%) in the ET group .UTIs were typically sparse, mild and caused by multisensitive bacteria. CONCLUSIONS: Complete trigonal and bladder neck mucosal fulguration promoted a significant reduction of UTI episodes during the first two years of follow-up. Prospective controlled studies are needed to determine the role of EF in women with RUTI. Source of Funding: none © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e458-e458 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Leopoldo Ribeiro-Filho More articles by this author Felipe Hirasaki More articles by this author Eduardo Miranda More articles by this author Matheus Siqueira More articles by this author Cristiano Gomes More articles by this author Miguel Srougi More articles by this author William Nahas More articles by this author Expand All Advertisement Loading ...

Analysis of a 440C steel roller bearing using finite element method

Abstract One of the important component of working machines or conveyer belt is the roller bearing. They are applied in different sectors ranging from automotive to heavy duty machineries in high speed drills. Their performance greatly affects the machines. This study illustrate the analysis of the contact stress developed in a roller bearing using ANSYS software. The Finite Element simulating results revels maximum stress distribution value of 6.597E-09 MPa under the applied loading condition appearing on the roller balls. The total moment for the variation to time is 2.5868E-07 experienced at 7.7 s while the relative rotation in the Z-direction is at its peak at 6 s. Therefore, this study shows that FEA in ANSYS has provide a faster and cheaper method compared to the production of numerous prototypes.

Experimental and finite element analysis of titanium based medial tibial condyle using incremental sheet metal forming

Incremental Sheet Metal Forming (ISMF) is an innovative manufacturing technique for producing prototypes and manufacturing of complex shaped sheet metal parts. Manufacturing of implants and prosthesis for biomedical applications is a challenging task, because it demands the fabrication of complex intricate structures replicating the shapes of human body parts. An attempt has been made to clearly describe the capabilities and limitations of a new manufacturing technology to fabricate low cost, specific design medical implants. This study aims to fabricate an implant for medial tibial condyle using single point incremental forming and thereby improve the suitability of the single point incremental forming process. This investigation reports the fundamental knowledge on mechanical behavior of titanium grade 2 sheet metal to design and fabrication of knee implants with rigid hemispherical and roller ball forming tools by means of single point incremental forming process. Influence of major process parameters such as forming force, deformation of sheet, sheet thickness and profile accuracy of part have been identified by experimental work and Finite Element (FE) simulations. The result has shown that surface finish of the part formed by the roller ball forming tool is better than hemispherical rigid tool.

Incremental stamping forming with use of roller ball tool in aluminum and magnesium alloy

The recent advance of the single-point incremental forming (SPIF) was possible by flexibility with used the Computer Numeric Control (CNC) machine and increase manufacture. The objective of this study is to investigate correlation between the limit angle, work-hardening, stress coefficient, and thickness in two alloys, an aluminum EN AW-1100 and magnesium AZ31-B. For this study, tests were on aluminum and magnesium plates with thickness 1 mm for stamping of cones, with a roller ball tool for conditions, spindle speeds 0 RPM, feed rate 1500 mm/min, and increment 0.01 mm/rot. The study points to a phenomenon with few observations so far, which is adhesion at the tip of the tool and influences the fracture in the material. The experimental results show that an adhesion is an indicator of premature fracture in the material, and favors the conformation of the material the increase of strength coefficient, and the reduction of the strain-hardening exponent of the hooloning equation favors the conformation of the material.

Effect of Self Myofascial Release Using Foam Roller Versus Tennis Ball in Subjects with Plantar Fasciitis:A Comparative Study

Background: Plantar fasciitis is a repetitive micro trauma overloaded injury of the attachment of plantar fascia at the inferior aspect of the calcaneum. It results into inflammation and thickening of the fascia causing heel pain. Myofascial release (MFR)is a manual therapy technique which can be used to release the tension developed in the thickened fascia. Self-Myofascial Release (SMFR) can be given with a variety of tools such as foam rollers and tennis ball. They are easy, harmless and cost effective method of giving SMFR. However, the efficacy of the technique in plantar fasciitis is not yet clear. Objective: To compare the effect of SMFR technique using foam roller and tennis ball in subjects with plantar fasciitis. Method: Thirty-twoeligible patients were recruited for the study. They were allocated into either group A (n = 16) and group B (n=16). Group A was given SMFR with Foam roller and group B was given SMFR with tennis ball. The intervention was given for 2 weeks (5 days/week). Visual analogue scale (VAS) and Foot and Ankle Disability Index (FADI) outcome measures were taken both at baseline and after 2 weeks of intervention. Results: Both group A and group B showed significant improvement in VAS and FADI after two weeks of interventions (p value 0.05) for both the outcome measures. Conclusion: This study concludes that SMFR with both foam roller and tennis ball showed improvement in pain and muscle function i.e. both interventions were equally effective. Neither of the method was found superior than the other.

Roller Massage: Comparing the Immediate Post-Treatment Effects Between an Instructional Video and a Self-Preferred Program Using Two Different Density-Type Roller Balls.

The aims of this study were to (1) compare the immediate post-treatment effects of an instructional video versus a self-preferred program on the hip range of motion and a pressure pain threshold using two different density roller balls, and (2) compare the effects of the two roller balls on those variables. Forty adults were randomly allocated into four groups: (1) MB1-video, (2) MB1-self-preferred, (3) MBX-video, and (4) MBX-self-preferred. Participants followed a video or a self-preferred program using either a moderate (MB1) or a hard (MBX) density ball. Main outcomes were passive hip internal rotation, external rotation, and a pressure pain threshold. For MB1, the video produced greater outcomes than the self-program for external rotation (10◦ versus 2◦), internal rotation (7◦ versus 2◦), and the pain threshold (210 kPa versus 44 kPa). For MBX, the video produced greater outcomes than the self-program for external rotation (8◦ versus 1◦), internal rotation (5◦ versus 1◦), and the pain threshold (184 kPa versus 30 kPa). When comparing roller balls, the MB1 produced greater outcomes than the MBX for external rotation (10◦ versus 8◦), internal rotation (7◦ versus 5◦), and the pain threshold (210 kPa versus 184 kPa) with the video. For the self-preferred program, the MB1 produced greater outcomes for external rotation (2◦ versus 1◦), internal rotation (2◦ versus 1◦), and the pain threshold (44 kPa versus 30 kPa). The instructional video and a moderate density ball produced greater immediate post-treatment outcomes than the self-program and a hard density ball. Professionals should consider using the video to teach technique and match clients to a specific density-type roller ball.

A Modern Writing Instrument Used as a Weapon for Committing Bank Cheque Fraud

In the recent era, investigation of dye, pigments and powder-based ink examination are big challenges. Literature and survey reveal that, some erasable ink pens were consistently used to commit economic frauds in bank instruments like cheques, withdrawal slips, demand drafts, fix deposit receipts, counterfeit currency, and other essential documents. Some manufacturers provide magic erasable writing instruments. Here, we deciphered this type of ink on different documents with the help of VSC-6000/HS. The main aim of this research work is to develop simple, rapid, sensitive, eco-friendly to retrieve original writings of erasable ink. Total of 640 test samples were prepared under the same conditions with different ink pens on different papers/cheques, where each sample was written with the ReWrite-erasable ink pen, thermal ink pen, roller ball high tech ink pen, normal ballpoint pen and gel pens for the comparison purpose. The test samples were examined under different types of scientific instruments, physical examination before and after exposing to different environmental conditions, sunlight and at room temperature (25o C) for the period of one hundred and eighty-one (181) days. This technique to retrieve the original disappeared writings done with a ReWrite-erasable ink pen is very easy, simple, rapid, non-destructive, eco-friendly, convenient and sensitive to detect manipulations done in forgery and in suspect documents. Detection of ghost strokes under VSC-6000/HS with different functions, like fluorescence spotlight and specific (300 to 365 nm) UV range will provide a new avenue by, which the forensic document scientist can identify the erased writing that might otherwise go undetected with other more frequently used methods.

Application of a Propeller-Based Air Propulsion System to the Land-Based Holonomic Vehicle

Holonomic vehicles with wheels such as ball wheels can move in any direction without rotating. For such a system, more driving motors and precise transmission mechanisms are necessary, which makes the control and fabrication complicated. This paper aims to present the design and construction of a novel holonomic mechanism to simplify the system. Air-based propulsion was applied to a land-based holonomic vehicle. A prototype with three roller balls was developed with a propeller for the propulsion of a triangular holonomic vehicle. Only two motors were applied, one for propeller rotation and the other for the adjustment of the angle of thrust. For the establishment of the methodology, the data, including propeller size, rotation per minute, velocity, thrust, efficiency, etc., were measured or calculated. The prototype can move at a velocity of approximate 0.558 m/s with an efficiency of 18.55%. Simulation results showed that with the increase of propulsion efficiency, the velocity can achieve more than 5 m/s if the efficiency is 70%. This study is the first attempt to apply air-based propulsion to a land-based holonomic vehicle. Further, the construction method is simple and can satisfy the accuracy requirement. This design method, therefore, will contribute to the application of holonomic vehicles due to the realization of holonomic functionality and simplicity.

Torque Reduction while Drilling With Casing

Currently, we have been witnessing the increasing number of problems in drilling caused by certain challenges in drilling through depleted reservoirs, complicated geological settings, and fast-growing technology of extended reach drilling. One of the methods used to solve the problems is casing-while-drilling. The authors have been studying the difficulties occurring while using this method with a special focus on the issue of torque increase while rotating a casing string at an excessive speed. The paper presents calculations of the torque taking into account the friction coefficient. As an effective solution to reduce the torque a new centralizer has been designed in the laboratory of the Department of Oil and Gas Well Drilling of Almetyevsk State Oil Institute. While performing casing drilling operations a new centralizer with roller balls attached makes it possible for rolling friction to be replaced with sliding friction and, thus, prevent thread stripping.

Efficiency of Inhibitive Mud Application in Horizontal Wells

Currently, we have been witnessing the increasing number of problems in drilling caused by certain challenges in drilling through depleted reservoirs, complicated geological settings, and fast-growing technology of extended reach drilling. One of the methods used to solve the problems is casing-while-drilling. The authors have been studying the difficulties occurring while using this method with a special focus on the issue of torque increase while rotating a casing string at an excessive speed. The paper presents calculations of the torque taking into account the friction coefficient. As an effective solution to reduce the torque a new centralizer has been designed in the laboratory of the Department of Oil and Gas Well Drilling of Almetyevsk State Oil Institute. While performing casing drilling operations a new centralizer with roller balls attached makes it possible for rolling friction to be replaced with sliding friction and, thus, prevent thread stripping.

An Introduction to Gel Inks: History and Analysis

With the increasing use and variety of gel pens on the market, forensic document examiners may encounter problems identifying gel pens from other common pen types. This study discusses the initial findings of an investigation into the history, technology, and properties of gel pens. Microscopical (visual) and chemical methods were also evaluated as ways to characterize and identify gel inks. The results of the study demonstrate that the presence of a gel ink can often be determined, but that some gel inks resemble other types of pens, especially roller balls, upon visual examination. Further, chromatographic methods used to characterize traditional dye-based inks may be less useful with gel inks; for these, other spectrometric methods including Raman spectroscopy and energy dispersive x-ray spectrometry (EDS) were evaluated and proved useful.&#x0D; Purchase Article - $10